Product development
Analytical Strategies to Improve Efficiency
Published
8 years agoon
By
adminProcess parameters are changed from time to time to reduce waste and improve efficiency. Analytical instrumentation provides the insight needed into these parameters, and can therefore hold the key to cement manufacturing process optimisation, says Dr Michael Caves.
The cement industry is one of the world?s most energy-intensive sectors. Cement is a crucial global commodity, indeed, usage levels are a useful indicator of economic activity. As an energy-intensive process, cement manufacturers are exposed to increasingly volatile energy prices. We will examine three successful strategies deployed by the cement industry, and the analytical instrumentation that has made them successful.
Smarter definition of product quality
The performance of cement is defined by its composition and fineness. Fineness defines cement performance, because it influences how fast the cement hydrates. Fineness is traditionally quantified by Blaine measurement, a surface area technique, but a recognised drawback of this method is that it only provides a single averaged figure for any given sample. As a result, two samples with the same Blaine may, in fact, contain different proportions of fines, and will therefore hydrate differently and have different strength characteristics.
Consider two model samples with different particle size distributions as shown in Figure 1. Each has the same Blaine value. When mixed with water, these two samples will hydrate differently. For example, the relatively high fines population in Sample 2 will hydrate very quickly, while higher levels of coarse particles in Sample 1 will extend the time taken for complete hydration.
This is a crucial limitation when it comes to optimising manufacturing, since it suggests that Blaine is not a fully reliable detector of whether a modification will impact product performance. Laser diffraction analysis, in contrast, provides a full particle size distribution for each cement sample, rather than a single averaged figure. This enables the correlation of discrete size fractions with critical aspects of cement performance, in a way that is simply not possible with Blaine measurement. This is the primary reason why laser diffraction particle sizing has become widely applied across the cement industry.
Correlations between particle size distribution data and cement performance reveal that different size fractions influence the key parameter of developed strength in various ways. For example, research has shown that particles less than 2 microns hydrate so quickly during product use that they can cause a cement to set exothermically and crack. Coarse particles (>50 microns in size), on the other hand, may fail to hydrate at all over the period of mixing, resulting in a micro-concrete. Strong correlations have been observed between early strength and the fraction of the sample which lies in the 3 – 30 micron range Ref. Figure 2, identifying this as a crucial size range for the control of cement performance. None of this more nuanced understanding can be developed from Blaine measurements.
In the finishing circuit it is common, yet highly inefficient, practice to over-grind, deliberately milling more than is necessary because a cement with higher overall fineness typically delivers acceptable strength characteristics, while one that is too coarse will usually be out of specification. Being able to set particle size specifications based on a sound understanding of the effect of each size fraction on product performance boosts operational confidence and supports the elimination of over-grinding. In fact, by switching to particle size analysis, it is possible to produce cement with higher one-day strength, but with a lower Blaine. In practical terms, this means less milling but a better quality product, a result that delivers a major gain in terms of energy consumption.
Automated process control
Alongside better product quality definition, laser diffraction particle sizing technology has been embraced by the cement industry because it provides options for continuous process monitoring. While Blaine is a manual method ill-suited to online implementation, laser diffraction is fast, highly automated and a well-established process analysis tool. Online systems can measure continuously, in real-time, with minimal manual input, and have the proven track record of reliability needed to drive automated control in a 24/7 operation, increasingly via sophisticated multivariate control platforms.
Just like a good operator, the automated system is simultaneously considering information from a number of sources, and manipulating a number of variables in response, to continually optimise the process. In general, automated systems are far more successful and efficient than a manual approach, provided that sufficient effort is put into developing a model and tuning the resulting control loops.
A switch from manual analysis and control to full automation can deliver significant energy savings. This is in addition to benefits such as increased throughput and a reduction in ball mill charge. All of these improvements drive up the efficiency of the overall process.
Change the product composition
Cement additives such as limestone or fly ash are now used routinely, bringing the economic advantage of being waste streams from other industries. However, their use brings new complexities to cement production.
Additional components in the cement increase the challenge of particle size optimisation, since each ingredient has the potential to perform differently and therefore should ideally have a discrete particle size distribution specification. Furthermore, ingredient replacement raises questions associated with operation of the grinding circuit, such as: ?Can all the ingredients be milled together or it is necessary to mill each ingredient separately and then blend them??
Instrumentation that combines Raman spectroscopy with automated imaging addresses this analytical requirement, enabling the technique of Morphologically-Directed Raman Spectroscopy (MDRS), which can be used to determine correlations between particle size, shape and chemical composition. For cement manufacturers, this makes it possible to investigate, for example, whether the components of a cement blend are represented equally across all size fractions. Aligning this information with product performance supports the development of precise specifications for the use of cement additives, which can then be used to establish and control processes for their inclusion.
Figure 3 illustrates the information that can be gathered using MDRS. Size data and Raman spectra were measured for a number of particles (typically in the region of 1,000). Comparing the Raman spectra with reference spectra enabled the chemical identification of different particle populations within the blend and the generation of a particle size distribution for each population.
This data suggests that the materials in this sample have been milled together, since the observed differences in particle size distribution correlate directly with differences in grindability between the three components. Clinker is a much harder material than limestone or slag, and if processed under comparable conditions would therefore be expected to exit the mill as the coarsest product. Even if the optimal particle size distribution for each component of the cement is identical, these results indicate that replacement materials cannot be milled alongside fresh clinker in the finishing circuits to produce the required optimised product.
Looking ahead
Successfully changing a process or ingredient to reduce waste and increase efficiency relies on a detailed understanding of the parameters that influence product performance and of how to effectively control the manufacturing process. Analytical instrumentation provides the insight needed to develop the necessary knowledge and can therefore hold the key to manufacturing process optimisation. The cement industry provides a powerful example of what can be achieved by embracing new analytical strategies and state-of-the-art techniques.
About the author
Dr Michael Caves is Business Development Manager, Malvern-Aimil Instruments. He has spent over 13 years working in various academic and commercial bioscience laboratories, analysing a range of materials in various contexts.
Laser diffraction analysis, in contrast, provides a full particle size distribution for each cement sample, rather than a single averaged figure.
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Marketing strategies of cement companies have undergone gradual transformation owing to the change in consumer behaviour. While TV commercials are high on humour and emotions to establish a fast connect with the customer, social media campaigns are focussed more on capturing the consumer’s attention in an over-crowded virtual world. Branding for cement companies has become a holistic growth strategy with quantifiable results. This has made brands opt for a mix package of traditional and new-age tools, such as social media. However, the hero of every marketing communication is the message, which encapsulates the unique selling points of the product. That after all is crux of the matter here.
While cement companies are effectively using marketing tools to reach out to the consumers, they need to strengthen the four Cs of the branding process – Consumer, Cost, Communication and Convenience. Putting up the right message, at the right time and at the right place for the right kind of customer demographic is of utmost importance in the long run. It is precisely for this reason that regional players are likely to have an upper hand as they rely on local language and cultural references to drive home the point. But modern marketing and branding domain is exponentially growing and it would be an interesting exercise to tabulate and analyse its impact on branding for cement.
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Indian cement industry is well known for its energy and natural resource efficiency
Published
2 years agoon
November 18, 2022By
adminDr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL) takes us through the multifaceted efforts that the company has undertaken to keep emissions in check with the use of alternative sources of energy and carbon capture technology.
Tell us about the policies of your organisation for the betterment of the environment.
Caring for people is one of the core values of our JK Lakshmi Cement Limited. We strongly believe that we all together can make a difference. In all our units, we have taken measures to reduce carbon footprint, emissions and minimise the use of natural resources. Climate change and sustainable development are major global concerns. As a responsible corporate, we are committed with and doing consistent effort small or big to preserve and enrich the environment in and around our area of operations.
As far as environmental policies are concerned, we are committed to comply with all applicable laws, standards and regulations of regulatory bodies pertaining to the environment. We are consistently making efforts to integrate the environmental concerns into the mainstream of the operations. We are giving thrust upon natural resource conservation like limestone, gypsum, water and energy. We are utilising different kinds of alternative fuels and raw materials. Awareness among the employees and local people on environmental concerns is an integral part of our company. We are adopting best environmental practices aligned with sustainable development goals.
Udaipur Cement Works Limited is a subsidiary of the JK Lakshmi Cement Limited. Since its inception, the company is committed towards boosting sustainability through adopting the latest art of technology designs, resource efficient equipment and various in-house innovations. We are giving thrust upon renewable and clean energy sources for our cement manufacturing. Solar Power and Waste Heat Recovery based power are our key ingredients for total power mix.
What impact does cement production have on the environment? Elaborate the major areas affected.
The major environmental concern areas during cement production are air emissions through point and nonpoint sources due to plant operation and emissions from mining operation, from material transport, carbon emissions through process, transit, noise pollution, vibration during mining, natural resource depletion, loss of biodiversity and change in landscape.
India is the second largest cement producer in the world. The Indian cement industry is well known for its energy and natural resource efficiency worldwide. The Indian cement industry is a frontrunner for implementing significant technology measures to ensure a greener future.
The cement industry is an energy intensive and significant contributor to climate change. Cement production contributes greenhouse gases directly and indirectly into the atmosphere through calcination and use of fossil fuels in an energy form. The industry believes in a circular economy by utilising alternative fuels for making cement. Cement companies are focusing on major areas of energy efficiency by adoption of technology measures, clinker substitution by alternative raw material for cement making, alternative fuels and green and clean energy resources. These all efforts are being done towards environment protection and sustainable future.
Nowadays, almost all cement units have a dry manufacturing process for cement production, only a few exceptions where wet manufacturing processes are in operation. In the dry manufacturing process, water is used only for the purpose of machinery cooling, which is recirculated in a closed loop, thus, no polluted water is generated during the dry manufacturing process.
We should also accept the fact that modern life is impossible without cement. However, through state-of-the-art technology and innovations, it is possible to mitigate all kinds of pollution without harm to the environment and human beings.
Tell us about the impact blended cement creates on the environment and emission rate.
Our country started cement production in 1914. However, it was introduced in the year 1904 at a small scale, earlier. Initially, the manufacturing of cement was only for Ordinary Portland Cement (OPC). In the 1980s, the production of blended cement was introduced by replacing fly ash and blast furnace slag. The production of blended cement increased in the growth period and crossed the 50 per cent in the year 2004.
The manufacturing of blended cement results in substantial savings in the thermal and electrical energy consumption as well as saving of natural resources. The overall consumption of raw materials, fossil fuel such as coal, efficient burning and state-of-the-art technology in cement plants have resulted in the gradual reduction of emission of carbon dioxide (CO2). Later, the production of blended cement was increased in manifolds.
If we think about the growth of blended cement in the past few decades, we can understand how much quantity of , (fly ash and slag) consumed and saved natural resources like limestone and fossil fuel, which were anyhow disposed of and harmed the environment. This is the reason it is called green cement. Reduction in the clinker to cement ratio has the second highest emission reduction potential i.e., 37 per cent. The low carbon roadmap for cement industries can be achieved from blended cement. Portland Pozzolana Cement (PPC), Portland Slag Cement (PSC) and Composite Cement are already approved by the National Agency BIS.
As far as kilogram CO2 per ton of cement emission concerns, Portland Slag Cement (PSC) has a larger potential, other than PPC, Composite Cement etc. for carbon emission reduction. BIS approved 60 per cent slag and 35 per cent clinker in composition of PSC. Thus, clinker per centage is quite less in PSC composition compared to other blended cement. The manufacturing of blended cement directly reduces thermal and process emissions, which contribute high in overall emissions from the cement industry, and this cannot be addressed through adoption of energy efficiency measures.
In the coming times, the cement industry must relook for other blended cement options to achieve a low carbon emissions road map. In near future, availability of fly ash and slag in terms of quality and quantity will be reduced due to various government schemes for low carbon initiatives viz. enhance renewable energy sources, waste to energy plants etc.
Further, it is required to increase awareness among consumers, like individual home builders or large infrastructure projects, to adopt greener alternatives viz. PPC and PSC for more sustainable
resource utilisation.
What are the decarbonising efforts taken by your organisation?
India is the world’s second largest cement producer. Rapid growth of big infrastructure, low-cost housing (Pradhan Mantri Awas Yojna), smart cities project and urbanisation will create cement demand in future. Being an energy intensive industry, we are also focusing upon alternative and renewable energy sources for long-term sustainable business growth for cement production.
Presently, our focus is to improve efficiency of zero carbon electricity generation technology such as waste heat recovery power through process optimisation and by adopting technological innovations in WHR power systems. We are also increasing our capacity for WHR based power and solar power in the near future. Right now, we are sourcing about 50 per cent of our power requirement from clean and renewable energy sources i.e., zero carbon electricity generation technology. Usage of alternative fuel during co-processing in the cement manufacturing process is a viable and sustainable option. In our unit, we are utilising alternative raw material and fuel for reducing carbon emissions. We are also looking forward to green logistics for our product transport in nearby areas.
By reducing clinker – cement ratio, increasing production of PPC and PSC cement, utilisation of alternative raw materials like synthetic gypsum/chemical gypsum, Jarosite generated from other process industries, we can reduce carbon emissions from cement manufacturing process. Further, we are looking forward to generating onsite fossil free electricity generation facilities by increasing the capacity of WHR based power and ground mounted solar energy plants.
We can say energy is the prime requirement of the cement industry and renewable energy is one of the major sources, which provides an opportunity to make a clean, safe and infinite source of power which is affordable for the cement industry.
What are the current programmes run by your organisation for re-building the environment and reducing pollution?
We are working in different ways for environmental aspects. As I said, we strongly believe that we all together can make a difference. We focus on every environmental aspect directly / indirectly related to our operation and surroundings.
If we talk about air pollution in operation, every section of the operational unit is well equipped with state-of-the-art technology-based air pollution control equipment (BagHouse and ESP) to mitigate the dust pollution beyond the compliance standard. We use high class standard PTFE glass fibre filter bags in our bag houses. UCWL has installed the DeNOx system (SNCR) for abatement of NOx pollution within norms. The company has installed a 6 MW capacity Waste Heat Recovery based power plant that utilises waste heat of kiln i.e., green and clean energy source. Also, installed a 14.6 MW capacity solar power system in the form of a renewable energy source.
All material transfer points are equipped with a dust extraction system. Material is stored under a covered shed to avoid secondary fugitive dust emission sources. Finished product is stored in silos. Water spraying system are mounted with material handling point. Road vacuum sweeping machine deployed for housekeeping of paved area.
In mining, have deployed wet drill machine for drilling bore holes. Controlled blasting is carried out with optimum charge using Air Decking Technique with wooden spacers and non-electric detonator (NONEL) for control of noise, fly rock, vibration, and dust emission. No secondary blasting is being done. The boulders are broken by hydraulic rock breaker. Moreover, instead of road transport, we installed Overland Belt Conveying system for crushed limestone transport from mine lease area to cement plant. Thus omit an insignificant amount of greenhouse gas emissions due to material transport, which is otherwise emitted from combustion of fossil fuel in the transport system. All point emission sources (stacks) are well equipped with online continuous emission monitoring system (OCEMS) for measuring parameters like PM, SO2 and NOx for 24×7. OCEMS data are interfaced with SPCB and CPCB servers.
The company has done considerable work upon water conservation and certified at 2.76 times water positive. We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24×7. All digital metres and level recorders are monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. Effluent Treatment Plant (ETP) installed for mine’s workshop. Treated water is reused in washing activity. The unit maintains Zero Liquid Discharge (ZLD).
Our unit has done extensive plantations of native and pollution tolerant species in industrial premises and mine lease areas. Moreover, we are not confined to our industrial boundary for plantation. We organised seedling distribution camps in our surrounding areas. We involve our stakeholders, too, for our plantation drive. UCWL has also extended its services under Corporate Social Responsibility for betterment of the environment in its surrounding. We conduct awareness programs for employees and stakeholders. We have banned Single Use Plastic (SUP) in our premises. In our industrial township, we have implemented a solid waste management system for our all households, guest house and bachelor hostel. A complete process of segregated waste (dry and wet) door to door collection systems is well established.
Tell us about the efforts taken by your organisation to better the environment in and around the manufacturing unit.
UCWL has invested capital in various environmental management and protection projects like installed DeNOx (SNCR) system, strengthening green belt development in and out of industrial premises, installed high class pollution control equipment, ground-mounted solar power plant etc.
The company has taken up various energy conservation projects like, installed VFD to reduce power consumption, improve efficiency of WHR power generation by installing additional economiser tubes and AI-based process optimisation systems. Further, we are going to increase WHR power generation capacity under our upcoming expansion project. UCWL promotes rainwater harvesting for augmentation of the ground water resource. Various scientifically based WHR structures are installed in plant premises and mine lease areas. About 80 per cent of present water requirement is being fulfilled by harvested rainwater sourced from Mine’s Pit. We are also looking forward towards green transport (CNG/LNG based), which will drastically reduce carbon footprint.
We are proud to say that JK Lakshmi Cement Limited has a strong leadership and vision for developing an eco-conscious and sustainable role model of our cement business. The company was a pioneer among cement industries of India, which had installed the DeNOx (SNCR) system in its cement plant.
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